Conventionally, a surface light source panel (lighting device) as shown in FIG. 1(a) is known (for example, refer to Patent Literature 1). As for such a surface light source panel 100, a layered structure (not shown) of an anode, an organic electroluminescence layer and a cathode intervenes between a transparent substrate 101 and a sealing substrate 102. Moreover, a sealing member 103 is formed to surround internal space between the edge parts of the transparent substrate 101 and the sealing substrate 102.
In recent years, as shown in FIG. 1(b), an effort to produce a pseudo-large-sized lighting device 110 is performed by arranging a plurality of comparatively small surface light source panels 100 in two dimensions. Thus, the reason for producing by using the plurality of surface light source panels 100 is that it takes into consideration for the manufacturing yield of the surface light source panel 100. That is, it is because the rate which becomes a defective product including a defect in proportion to size will increase and the yield will worsen, when producing a large-sized lighting device by using a single surface light source panel 100.
[Patent Literature 1] Japanese Patent Application Laying-Open Publication No. 2005-38661